Horlicks could be about to disclose the 130-year-old secret behind why the
malt drink helps people to sleep.

The product has been promoted as a bedtime essential for decades without an explanation as to how it works.

But a relaunch of the brand later this year is expected to include the first scientific evidence behind the claim, according to a trade magazine Marketing.

Horlicks was first created when brothers James and William Horlick, from Gloucestershire, founded a company in the US to manufacture a patented malt milk drink as an artificial infant food.

As a company we are trying to be more responsible and use science to back up the claims we make

Kathleen McGrathGlaxoSmithKline

The brand has been advertised with a sleep message since the 1920s.

But GlaxoSmithKline, maker of Horlicks, has always been unable to explain the
science behind the claim.

Vitamins and iron

Kathleen McGrath, from GlaxoSmithKline, said: "We have been working with sleep experts for the past four or five years trying to see why nutritional drinks, and particularly warm drinks, help to deliver sleep.

"Also, as a company we are trying to be more responsible and use science to back up the claims we make."

One theory for why Horlicks works is its combinations of vitamins plus folic acid and iron.

In addition, a warm drink before bedtime increases then lowers body temperature which is also thought to aid sleep, which is why some people believe a hot bath helps.